The present invention relates to multi-phase detergent tablets. In particular, it relates to multi-phase detergent tablets having improved robustness and product integrity together with excellent dissolution characteristics.
Detergent compositions in tablet form are known in the art. It is understood that detergent compositions in tablet form hold several advantages over detergent compositions in particulate form, such as ease of dosing, handling, transportation and storage.
Detergent tablets are most commonly prepared by pre-mixing components of a detergent composition and forming the pre-mixed detergent components into a tablet using any suitable equipment, preferably a tablet press. Tablets are typically formed by compression of the components of the detergent composition so that the tablets produced are sufficiently robust to be able to withstand handling and transportation without sustaining damage. In addition to being robust, tablets must also dissolve sufficiently fast so that the detergent components are released into the wash water as soon as possible at the beginning of the wash cycle.
However, a dichotomy exists in that as compression force is increased, the rate of dissolution of the tablets becomes slower. The present invention therefore seeks to find a balance between tablet robustness and tablet dissolution.
Solutions to this problem, as seen in the prior art, have included compressing the tablets with low compression pressure. However tablets made in this way, although having a fast relative dissolution rate, tend to crumble, becoming damaged and unacceptable to the consumer. Other solutions have included preparing tablets using a high relative compression pressure, in order to achieve the required level of robustness, and comprising a dissolution aid, such as an effervescent agent.
Multi-phase detergent tablets described in the prior art are prepared by compressing a first composition in a tablet press to form a substantially planar first layer. A further detergent composition is then delivered to the tablet press on top of the first layer. This second composition is then compressed to form another substantially planar second layer. Thus the first layer is generally subjected to more than one compression as it is also compressed during the compression of the second composition. Typically the first and second compression forces are in the same order of magnitude. The Applicant has found that where this is the case, because the compression force must be sufficient to bind the first and second compositions together, the force used in both the first and second compression steps must be in the range of from about 4,000 to about 20,000 kg (assuming a tablet cross-section of about 10 cm2). A consequence of this is a slower rate of tablet dissolution. Other multi-phase tablets exhibiting differential dissolution are prepared such that the second layer is compressed at a lower force than the first layer. However, although the dissolution rate of the second layer is improved, the second layer is soft in comparison to the first layer and is therefore vulnerable to damage caused by handling and transportation. Moreover, the two layers are found to have poor adhesion characteristics and can break up under the relatively mild stress conditions found in storage or transportation.
The present invention therefore provides multi-phase detergent tablets for use in automatic dishwashing, laundry, etc and which have improved integrity and robustness together with excellent dissolution characteristics.
According to a first aspect of the invention, there is provided a multi-phase detergent tablet for use in a washing machine, the tablet comprising a first phase in adhesive contact with one or more second phases, at least one second phase being in the form of a compressed particulate solid incorporating liquid adhesive and having an average porosity of less than about 0.15 ml/g, preferably less than about 0.13 ml/g and more preferably less than about 0.11 ml/g.
Porosity can be measured by known methods including image analysis, mercury porosimetry, determination and comparison of volume and mass, determination and comparison of surface area and diameter, gas chromatography, x-ray small angle scattering and displacement methods. A preferred method of measuring porosity is the mercury porosimetry method, average porosity being defined as the total intrusion volume of the particulate solid (prior to introduction of the liquid adhesive) for pore volumes below 30 xcexcm. Preferably, the compressed particulate solid has an average porosity of less than about 0.09 ml/g, more preferably less than about 0.07 ml/g and especially less than about 0.05 ml/g.
In preferred embodiments, the adhesive is liquid or fluid at or close to ambient temperatures (preferably 28xc2x0 C., more preferably 25xc2x0 C. and above). It is also preferred herein to use adhesives that are water-frangible or water-sensitive, for example, adhesives based on water-soluble or water-emulsifiable polymers. It will also be understood that water and other solvent-based adhesives, for example, adhesives comprising aqueous polymeric solutions or emulsions, are also suitable for use herein. However, the preferred adhesives are either water-free or are used in conjunction with a water-sink (for example, anhydrous builder salts) in order to minimise the free moisture content of the final tablet compositions which is preferably less than about 1% by weight. The liquid adhesive is incorporated by post-addition, preferably as a spray-on, to the particulate solid prior to compression. The level of liquid adhesive is preferably from about 0.1% to about 3%, more preferably from about 0.5% to about 1.5% by weight of the second phase particulate solid.
In preferred embodiments, the first phase also takes the form of a compressed particulate solid, the average porosity of which is greater than that of the second phase particulate solid by at least 10%, preferably at least 30%, and more preferably at least 60%, this being valuable for optimum adhesion. In general, the average porosity of the first phase is at least 0.1 ml/g, preferably at least 0.12 ml/g, more preferably at least 0.14 ml/g, especially at least 0.16 ml/g and more especially at least 0.18 ml/g. Preferred adhesives for use herein are selected from water-soluble poly(C2-C4)-alkylene oxide polymers and copolymers, poly(C2-C4)-alkoxylated nonionic surfactants, aqueous polymeric solutions and emulsions, and mixtures thereof. Of these, highly preferred from the viewpoint of optimum product integrity, robustness and dissolution characteristics are the polyethylene glycols having an average molecular weight in the range from about 200 to about 700, preferably from about 250 to about 600, although polyethylene glycols of a somewhat higher average molecular weight, for example up to about 900, can be used if the detergent tablet is prepared at a temperature slightly above ambient, for example up to about 28xc2x0 C.
Thus according to second aspect of the invention, there is provided a multi-phase detergent tablet for use in a washing machine, the tablet comprising a first phase in adhesive contact with one or more second phases, at least one second phase being in the form of a compressed particulate solid incorporating liquid adhesive selected from polyethylene glycols having an average molecular weight in the range from about 200 to about 700.
The detergent tablets herein comprise at least one first phase in adhesive contact with one or more second phases (sometimes referred to herein as xe2x80x98optional subsequent phasesxe2x80x99). In preferred embodiments, the first phase is a compressed shaped body prepared at an applied compression pressure of at least about 250 kg/cm2, preferably at least about 350 kg/cm2 (3.43 kN/cm2 or 34.3 MPa), more preferably from about 400 to about 2000 kg/cm2, and especially from about 600 to about 1200 kg/cm2 (compression pressure herein is the applied force divided by the cross-sectional area of the tablet in a plane transverse to the applied forcexe2x80x94in effect, the transverse cross-sectional area of the die of the rotary press). The second phase, on the other hand, is preferably formed at a compression pressure of less than about 350 kg/cm2, preferably in the range from about 40 kg/cm2 to about 300 kg/cm2 and more preferably from about 70 to about 270 kg/cm2. In preferred embodiments, moreover, the first phase is formed by compression at a pressure greater than that applied to the second phase. In these embodiments, the compression pressures applied to the first and second phases will generally be in a ratio of at least about 1.2:1, preferably at least about 2:1, more preferably at least about 4:1.
Preferred herein from the viewpoint of providing optimum interphase adhesivity and robustness are tablets and processes wherein the liquid adhesive is incorporated by post-addition to the particulate solid of the second phase prior to compression thereof. Post-addition preferably takes the form of a spray-on of the liquid adhesive to the particulate solid and normally will take place as a final step shortly before compression, preferably within about 1 day, and more preferably within about 12 hours.
Thus, according to a further aspect of the invention, there is provided a multi-phase detergent tablet for use in a washing machine, the tablet comprising a first phase in adhesive contact with one or more second phases, at least one second phase being in the form of a compressed particulate solid incorporating liquid adhesive and wherein the liquid adhesive is incorporated by post-addition, preferably as a spray-on, to the particulate solid prior to compression.
Although simple multi-layer tablets are envisaged for use herein, preferred from the viewpoint of optimum product integrity, strength (measured for example by the Child Bite Strength [CBS] test) and dissolution characteristics are tablets wherein the first phase is in the form of a shaped body having at least one mould therein; and the second phase is in the form of a particulate solid compressed within said mould. Such embodiments are sometimes referred to herein as xe2x80x98mouldxe2x80x99 embodiments. The tablets of the invention, both mould embodiments and otherwise, will preferably have a CBS of at least about 8 kg, preferably greater than about 10 kg, more preferably greater than about 12 kg, and especially greater than about 14 kg, CBS being measured per the US Consumer Product Safety Commission Test Specification.
It is also preferred that the first and second phases herein are in a relatively high weight ratio to one another, for example at least about 6:1, preferably at least about 10:1; also that the tablet composition contain one or more detergent actives (for example enzymes, bleaches, bleach activators, bleach catalysts, surfactants, chelating agents etc) which is predominantly concentrated in the second phase, for example, at least about 50%, preferably at least about 60%, especially about 80% by weight of the active (based on the total weight of the active in tablet) is in the second phase of the tablet. Again, such compositions are optimum for tablet strength, dissolution, cleaning, and pH regulation characteristics providing, for example, tablet compositions capable of dissolving in the wash liquor so as to deliver at least 50%, preferably at least 60%, and more preferably at least 80% by weight of the detergent active to the wash liquor within 10, 5, 4 or even 3 minutes of the start of the wash process.
It is an object of the present invention to provide a detergent tablet that is not only sufficiently robust to withstand handling and transportation, but also at least a significant portion of which dissolves rapidly in the wash water providing rapid delivery of detergent active. It is preferred that at least one phase of the tablet dissolves in the wash water within the first ten minutes, preferably five minutes, more preferably four minutes of the wash cycle of an automatic dishwashing or laundry washing machine. Preferably the washing machine is either an automatic dishwashing or laundry washing machine. The time within which the multi-phase tablet or a phase thereof or a detergent active component dissolves is determined according to DIN 44990 using a dishwashing machine available from Bosch on the normal 65xc2x0 C. washing program with water hardness at 18xc2x0 H using a minimum of six replicates or a sufficient number to ensure reproducibility.
The multi-phase detergent tablet of the present invention comprises a first phase, a second and optional subsequent phases. The first phase is in the form of a shaped body of detergent composition comprising one or more detergent components as described below. Preferred detergent components include, builder, bleach, enzymes and surfactant. The components of the detergent composition are mixed together by, for example admixing dry components or spraying-on liquid components. The components are then formed into a first phase using any suitable equipment, but preferably by compression, for example in a tablet press. Alternatively, the first phase can be prepared by extrusion, casting, etc.
In mould embodiments, the first phase is prepared such that it comprises at least one mould in the surface of the shaped body. In a preferred embodiment the mould is created using a specially designed tablet press wherein the surface of the punch that contacts the detergent composition is shaped such that when it contacts and presses the detergent composition it presses a mould, or multiple moulds into the first phase of the multi-phase detergent tablet. Preferably, the mould will have an inwardly concave or generally concave surface to provide improved adhesion to the second phase.
The tablets of the invention also include one or more additional phases prepared from a composition or compositions which comprise one or more detergent components as described below. At least one phase (herein referred to as a second phase) preferably takes the form of a particulate solid (which term encompasses powders, granules, agglomerates, and other particulate solids including mixtures thereof with liquid binders, meltable solids, spray-ons, etc) compressed either as a layer or into/within the one or more moulds of the first phase of the detergent tablet such that the second phase itself takes the form of a shaped body. Preferred detergent components include builders, colourants, binders, surfactants, disrupting agents and enzymes, in particular amylase and protease enzymes. In another preferred aspect of the present invention the second and optional subsequent phases comprise a disrupting agent that may be selected from either a disintegrating agent or an effervescent agent. Suitable disintegrating agents include agents that swell on contact with water or facilitate water influx and/or efflux by forming channels in the detergent tablet. Any known disintegrating or effervescing agent suitable for use in laundry or dishwashing applications is envisaged for use herein. Suitable disintegrating agent include starch, starch derivatives such as Arbocel (tradename), Vivapur (tradename) both available from Rettenmaier, Nymcel (tradename) available from Metsa-serla, alginates, acetate trihydrate, burkeite, monohydrated carbonate formula Na2CO3.H2O, hydrated STPP with a phase I content of at least about 40%, carboxymethylcellulose (CMC), CMC-based polymers, sodium acetate, aluminium oxide. Suitable effervescing agents are those that produce a gas on contact with water. Suitable effervesing agents may be oxygen, nitrogen dioxide or carbon dioxide evolving species. Examples of preferred effervescent agents may be selected from the group consisting of perborate, percarbonate, carbonate, bicarbonate in combination with inorganic acids such as sulphamic acid and/or carboxylic acids such as citric, malic and maleic acid and mixtures thereof
The components of the detergent composition are mixed together by for example premixing dry components and admixing, preferably by spray-on, the adhesive and other liquid components. The components of the second and optional subsequent phases are then compressed to form one or more layers or are fed into and retained within the mould provided by the first phase.
The preferred mould embodiments of the present invention comprises two phases; a first and a second phase. The first phase will normally comprise one mould and the second phase will normally consist of a single detergent active composition. However, it is envisaged that the first phase may comprise more than one mould and the second phase may be prepared from more than one detergent active composition. Furthermore, it is also envisaged that the second phase may comprise more than one detergent active composition contained within one mould. It is also envisaged that several detergent active compositions are contained in separate moulds. In this way potentially chemically sensitive detergent components can be separated in order to avoid any loss in performance caused by components reacting together and potentially becoming inactive or exhausted.
In a preferred aspect of the present invention the first, second and/or optional subsequent phases may comprise a binder. Where present the binder is selected from the group consisting of organic polymers, for example polyethylene and/or polypropylene glycols having an average molecular weight of from about 1000 to about 12000, especially those of molecular weight 4000, 6000 and 9000, polyvinyl pyrolindone (PVP), especially PVP of molecular weight 90 000, polyacrylates, sugars and sugar derivatives, starch and starch derivatives, for example hydroxy propyl methyl cellulose (HPMC) and carboxy methyl cellulose (CMC); and inorganic polymers, such as hexametaphosphate. The polyethyleneglycol binders are highly preferred herein. The combination of liquid adhesive and binder is particularly valuable from the viewpoint of providing improved interphase adhesivity and robustness.
In a preferred aspect of the present invention the first phase weighs greater than 5 g. More preferably the first phase weighs from 10 g to 30 g, even more preferably from 15 g to 25 g and most preferably form 18 g to 24 g. The second and optional subsequent phases weigh less than 4 g. More preferably the second and/or optional subsequent phases weigh between 1 g and 3.5 g, most preferably from 1.3 g to 2.5 g.
The components of the second and optional subsequent phases are compressed, especially in the mould embodiments, at a much lower compression force relative to the compression force normally used to prepare high strength tablets. At the same time, the tablets of the invention display excellent adherence between phases and product integrity. Thus an advantage of the present invention is that because a lower compression force is used heat, force or chemically sensitive detergent components can be incorporated into the detergent tablet without sustaining the consequential loss in performance usually encountered when incorporating such components into tablets.
Yet another advantage of the present invention is the ability to prepare a multi-phase detergent tablet wherein one phase can be designed to dissolve, preferably significantly before another phase. In the present invention it is preferred that the second and optional subsequent phase(s) dissolves before the first phase. According to the preferred weight ranges described above, it preferable that the first phase dissolves in from 5 to 20 minutes, more preferably from 10 to 15 minutes and the second and/or optional subsequent phases dissolve in less than 5 minutes, more preferably less than 4.5 minutes, most preferably less than 4 minutes. The time in which the first, second and/or optional subsequent phase dissolve are independent from each other. Thus in a particularly preferred aspect of the present invention differential dissolution of the phases is achieved. A particular benefit of being able to achieve differential dissolution of the multi-phase detergent tablet is that a component that is chemically inactivated by the presence of another component can be separated into a different phase. In this case the component that is inactivated is preferably located in the second and optional subsequent phase(s).
The multi-phase detergent tablets are prepared using any suitable tabletting equipment. Preferably the tablets are prepared by compression in a tablet press capable of preparing a tablet comprising a mould. In a particularly preferred embodiment of the present invention the first phase is prepared using a specially designed tablet press. The punch(es) of this tablet press are modified so that the surface of the punch that contacts the detergent composition has a convex surface.
A first detergent composition is delivered into the die of the tablet press and the punch is lowered to contact and then compress the detergent composition to form a first phase. The first detergent composition is compressed using an applied pressure of at least 250 kg/cm2, preferably between 350 and 2000 kg/cm2, more preferably 500 to 1500 kg/cm2, most preferably 600 to 1200 kg/cm2. The punch is then elevated, exposing the first phase containing a mould. A second and optional subsequent detergent composition(s) is then delivered into the mould. The specially designed tablet press punch is then lowered a second time to lightly compress the second and optional subsequent detergent composition(s) to form the second and optional subsequent phase(s). In another embodiment of the present invention where an optional subsequent phase is present the optional subsequent phase is prepared in an optional subsequent compression step substantially similar to the second compression step described above. The second and optional subsequent detergent composition(s) is compressed at a pressure of preferably less than 350 kg/cm2, more preferably from 40 to 300 kg/cm2, most preferably from 70 to 270 kg/cm2. After compression of the second detergent composition, the punch is elevated a second time and the multi-phase detergent tablet is ejected from the tablet press. Multi-layer tablets without moulds can be prepared in a similar manner except using a tablet punch having a planar surface.
The first and second and or optional subsequent phases of the multi-phase detergent tablet described herein are prepared by compression of one or more compositions comprising detergent active components. Suitably, the compositions used in any of these phases may include a variety of different detergent components including builder compounds, surfactants, enzymes, bleaching agents, alkalinity sources, colourants, perfume, lime soap dispersants, organic polymeric compounds including polymeric dye transfer inhibiting agents, crystal growth inhibitors, heavy metal ion sequestrants, metal ion salts, enzyme stabilisers, corrosion inhibitors, suds suppressers, solvents, fabric softening agents, optical brighteners and hydrotropes. In the following, the proportions of these active components are given by weight of the corresponding composition of active detergent components, unless specified otherwise.
Highly preferred detergent components of the first phase include a builder compound, a surfactant, an enzyme and a bleaching agent. Highly preferred detergent components of the second phase include builder, enzymes and disrupting agent.
Builders suitable for use herein include water-soluble builders such as citrates, carbonates and polyphosphates and partially water-soluble or insoluble builders such as crystalline layered silicates (EP-A-0164514 and EP-A-0293640) and aluminosilicates inclusive of Zeolites A, B, P, X, HS and MAP. The builder is typically present at a level of from about 1% to about 80% by weight, preferably from about 10% to about 70% by weight, most preferably from about 20% to about 60% by weight of composition.
Surfactants suitable herein include anionic surfactants such as alkyl sulfates, alkyl ether sulfates, alkyl benzene sulfonates, alkyl glyceryl sulfonates, alkyl and alkenyl sulphonates, alkyl ethoxy carboxylates, N-acyl sarcosinates, N-acyl taurates and alkyl succinates and sulfosuccinates, wherein the alkyl, alkenyl or acyl moiety is C5-C20, preferably C10-C18 linear or branched; cationic surfactants such as choline esters (U.S. Pat. Nos. 4,228,042, 4,239,660 and 4,260,529) and mono C6-C16 N-alkyl or alkenyl ammonium surfactants wherein the remaining N positions are substituted by methyl, hydroxyethyl or hydroxypropyl groups; low and high cloud point nonionic surfactants and mixtures thereof including nonionic alkoxylated surfactants (especially ethoxylates derived from C6-C18 primary alcohols), ethoxylated-propoxylated alcohols (e.g., Olin Corporation""s Poly-Tergent(copyright) SLF18), epoxy-capped poly(oxyalkylated) alcohols (e.g., Olin Corporation""s Poly-Tergent(copyright) SLF 18Bxe2x80x94see WO-A-94/22800), ether-capped poly(oxyalkylated) alcohol surfactants, and block polyoxyethylene-polyoxypropylene polymeric compounds such as PLURONIC(copyright), REVERSED PLURONIC(copyright), and TETRONIC(copyright) by the BASF-Wyandotte Corp., Wyandotte, Mich.; amphoteric surfactants such as the amine oxides and alkyl amphocarboxylicc surfactants such as Miranol(trademark) C2M; and zwitterionic surfactants such as the betaines and sultaines; and mixtures thereof. Surfactants suitable herein are disclosed, for example, in U.S. Pat. Nos. 3,929,678, 4,259,217, EP-A-0414 549, WO-A-93/08876 and WO-A-93/08874. Surfactants are typically present at a level of from about 0.2% to about 30% by weight, more preferably from about 0.5% to about 10% by weight, most preferably from about 1% to about 5% by weight of composition.
Enzymes suitable herein include bacterial and fungal cellulases such as Carezyme and Celluzyme (Novo Nordisk A/S); peroxidases; lipases such as Amano-P (Amano Pharmaceutical Co.), M1 Lipase(copyright) and Lipomax(copyright) (Gist-Brocades) and Lipolase(copyright) and Lipolase Ultra(copyright) (Novo); cutinases; proteases such as Esperase(copyright), Alcalase(copyright), Durazym(copyright) and Savinase(copyright) (Novo) and Maxatase(copyright), Maxacal(copyright), Properase(copyright) and Maxapem(copyright) (Gist-Brocades); and xcex1 and xcex2 amylases such as Purafect Ox Am(copyright) (Genencor) and Termamyl(copyright), Ban(copyright), Fungamyl(copyright), Duramyl(copyright), and Natalase(copyright) (Novo); and mixtures thereof. Enzymes are preferably added herein as prills, granulates, or cogranulates at levels typically in the range from about 0.0001% to about 2% pure enzyme by weight of composition.
Bleaching agents suitable herein include chlorine and oxygen bleaches, especially inorganic perhydrate salts such as sodium perborate mono-and tetrahydrates and sodium percarbonate optionally coated to provide controlled rate of release (see, for example, GB-A-1466799 on sulfate/carbonate coatings), preformed organic peroxyacids and mixtures thereof with organic peroxyacid bleach precursors and/or transition metal-containing bleach catalysts (especially manganese or cobalt). Inorganic perhydrate salts are typically incorporated at levels in the range from about 1% to about 40% by weight, preferably from about 2% to about 30% by weight and more preferably from abut 5% to about 25% by weight of composition. Peroxyacid bleach precursors preferred for use herein include precursors of perbenzoic acid and substituted perbenzoic acid; cationic peroxyacid precursors; peracetic acid precursors such as TAED, sodium acetoxybenzene sulfonate and pentaacetylglucose; pernonanoic acid precursors such as sodium 3,5,5-trimethylhexanoyloxybenzene sulfonate (iso-NOBS) and sodium nonanoyloxybenzene sulfonate (NOBS); amide substituted alkyl peroxyacid precursors (EP-A-0170386); and benzoxazin peroxyacid precursors (EP-A-0332294 and EP-A-0482807). Bleach precursors are typically incorporated at levels in the range from about 0.5% to about 25%, preferably from about 1% to about 10% by weight of composition while the preformed organic peroxyacids themselves are typically incorporated at levels in the range from 0.5% to 25% by weight, more preferably from 1% to 10% by weight of composition. Bleach catalysts preferred for use herein include the manganese triazacyclononane and related complexes (U.S. Pat. Nos. 4,246,612, 5,227,084); Co, Cu, Mn and Fe bispyridylamine and related complexes (U.S. Pat. No. 5,114,611); and pentamine acetate cobalt(III) and related complexes(U.S. Pat. No. 4,810,410).
Other suitable components herein include organic polymers having dispersant, anti-redeposition, soil release or other detergency properties invention in levels of from about 0.1% to about 30%, preferably from about 0.5% to about 15%, most preferably from about 1% to about 10% by weight of composition. Preferred anti-redeposition polymers herein include acrylic acid containing polymers such as Sokalan PA30, PA20, PA15, PA10 and Sokalan CP10 (BASF GmbH), Acusol 45N, 480N, 460N (Rohm and Haas), acrylic acid/maleic acid copolymers such as Sokalan CP5 and acrylic/methacrylic copolymers. Preferred soil release polymers herein include alkyl and hydroxyalkyl celluloses (U.S. Pat. No. 4,000,093), polyoxyethylenes, polyoxypropylenes and copolymers thereof, and nonionic and anionic polymers based on terephthalate esters of ethylene glycol, propylene glycol and mixtures thereof.
Heavy metal sequestrants and crystal growth inhibitors are suitable for use herein in levels generally from about 0.005% to about 20%, preferably from about 0.1% to about 10%, more preferably from about 0.25% to about 7.5% and most preferably from about 0.5% to about 5% by weight of composition, for example diethylenetriamine penta (methylene phosphonate), ethylenediamine tetra(methylene phosphonate) hexamethylenediamine tetra(methylene phosphonate), ethylene diphosphonate, hydroxy-ethylene-1,1-diphosphonate, nitrilotriacetate, ethylenediaminotetracetate, ethylenediamine-N,Nxe2x80x2-disuccinate in their salt and free acid forms.
The compositions herein, especially for use in dishwashing, can contain a corrosion inhibitor such as organic silver coating agents in levels of from about 0.05% to about 10%, preferably from about 0.1% to about 5% by weight of composition (especially paraffins such as Winog 70 sold by Wintershall, Salzbergen, Germany), nitrogen-containing corrosion inhibitor compounds (for example benzotriazole and benzimadazolexe2x80x94see GB-A-1137741) and Mn(II) compounds, particularly Mn(II) salts of organic ligands in levels of from about 0.005% to about 5%, preferably from about 0.01% to about 1%, more preferably from about 0.02% to about 0.4% by weight of the composition.
Other suitable components herein include colourants, water-soluble bismuth compounds such as bismuth acetate and bismuth citrate at levels of from about 0.01% to about 5%, enzyme stabilizers such as calcium ion, boric acid, propylene glycol and chlorine bleach scavengers at levels of from about 0.01% to about 6%, lime soap dispersants (see WO-A-93/08877), suds suppressors (see WO-93/08876 and EP-A-0705324), polymeric dye transfer inhibiting agents, optical brighteners, perfumes, fillers and clay and cationic fabric softeners.
Detergent components suitable for use herein are described in more detail in the Appendix to the Description (Ref: ADWIL)
The detergent tablets herein are preferably formulated to have a not unduly high pH, preferably a pH in 1% solution in distilled water of from about 8.0 to about 12.5, more preferably from about 9.0 to about 11.8, most preferably from about 9.5 to about 11.5.
A preferred machine dishwashing method comprises treating soiled articles selected from crockery, glassware, silverware, metallic items, cutlery and mixtures thereof, with an aqueous liquid having dissolved or dispensed therein an effective amount of a the herein described compositions. By an effective amount is meant from 8 g to 60 g of product dissolved or dispersed in a wash solution of volume from 3 to 10 litres, as are typical product dosages and wash solution volumes commonly employed in conventional machine dishwashing methods. Preferably the detergent tablets are from 15 g to 40 g in weight, more preferably from 20 g to 35 g in weight.
Machine laundry methods herein typically comprise treating soiled laundry with an aqueous wash solution in a washing machine having dissolved or dispensed therein an effective amount of the herein described compositions. By an effective amount is meant from 40 g to 300 g of product dissolved or dispersed in a wash solution of volume from 5 to 65 litres, as are typical product dosages and wash solution volumes commonly employed in conventional machine laundry methods.
In a preferred use aspect a dispensing device is employed in the washing method. The dispensing device is charged with the detergent product, and is used to introduce the product directly into the drum of the washing machine before the commencement of the wash cycle. Its volume capacity should be such as to be able to contain sufficient detergent product as would normally be used in the washing method.
To allow for release of the detergent product during the wash the device may possess a number of openings through which the product may pass. Alternatively, the device may be made of a material which is permeable to liquid but impermeable to the solid product, which will allow release of dissolved product. Preferably, the detergent product will be rapidly released at the start of the wash cycle thereby providing transient localised high concentrations of product in the drum of the washing machine at this stage of the wash cycle.
Preferred dispensing devices are reusable and are designed in such a way that container integrity is maintained in both the dry state and during the wash cycle.
Alternatively, the dispensing device may be a flexible container, such as a bag or pouch. The bag may be of fibrous construction coated with a water impermeable protective material so as to retain the contents, such as is disclosed in EP-A-0018678. Alternatively it may be formed of a water-insoluble synthetic polymeric material provided with an edge seal or closure designed to rupture in aqueous media as disclosed in EP-A-0011500, EP-A-0011501, EP-A-0011502, and EP-A-0011968. A convenient form of water frangible closure comprises a water soluble adhesive disposed along and sealing one edge of a pouch formed of a water impermeable polymeric film such as polyethylene or polypropylene.